The present disclosure relates to a seat sliding device for vehicle.
A seat sliding device for a vehicle disclosed in Japanese Patent Application Publication No. 2010-36609 (Patent Document 1) comprises a lower rail and an upper rail. The lower rail is provided on a floor side of the vehicle. The upper rail slidably engages with the lower rail. The upper rail is attached to a seat.
The upper rail comprises a rolling element. An outer peripheral surface of the rolling element is in contact with the lower rail. When the upper rail slides relative to the lower rail, the rolling element rolls.
The upper rail comprises a concave step in the vicinity of the rolling element. A shoe portion made of resin is attached to the concave step. The shoe portion is slidable in the concave step in a longitudinal direction of the upper rail. The shoe portion is brought into contact with the rolling element when it slides in a first direction in the concave step. The shoe portion moves away from the rolling element when it slides in a second direction opposite to the first direction in the concave step. In addition, the shoe portion is always in contact with the lower rail at its upper end.
When the upper rail slides in the second direction, a force in the first direction is applied to the shoe portion by the upper rail. Consequently, the shoe portion slides in the first direction in the concave step. Therefore, the shoe portion is brought into contact with the rolling element, and rolling resistance of the rolling element increases. As a result, resistance in sliding the upper rail increases.
In contrast, when the upper rail slides in the first direction, the shoe portion slides in the second direction in the concave step. Therefore, the shoe portion moves away from the rolling element, and rolling resistance of the rolling element does not increase. As a result, resistance in sliding the upper rail does not increase.
Accordingly, in the technique disclosed in Patent Document 1, when the upper rail slides in the second direction, resistance in sliding is large. When the upper rail slides in the first direction, resistance in sliding is small.